Catalytic combustion of polychlorinated biphenyls in monolith reactors

The catalytic combustion of Aroclor 1242 (consisting of polychlorinated biphenyls, PCBs) was studied using a single channel monolith reactor of 15 mm i.d. and lengths varying from 150 to 310 mm. Experiments were performed at gas hourly space velocities in the range of 6×10³ to 13×10³ h^-1 and inlet temperatures >740 K. The catalyst used was chromia on an alumina support for ceramic substrates, and chromia on zirconia for the metal inserts; catalyst coating techniques are also described. Reaction experiments were performed with varying internal designs for the monolith reactor, that is, with and without the use of catalyst coated inserts. A technique of coating the metal insert with a ceramic substrate prior to catalyst loading is described. The catalyst coated insert substantially enhanced the performance of the reactor. Reaction experiments in a segmented multichannel catalytic monolith showed that fractional conversions of PCBs in excess of 0.99 can be achieved. A single channel annular flow model has also been used as a diagnostic tool to interpret the experimental results.